This study presents the use of imagery from Unmanned Aerial Vehicle (UAV) as a primary means of structural geological data collection, complimented by traditional methods to assess the stability of high rock slopes along the Rugtvedt-Dørdal section of the E-18 highway under construction in Norway. The road has about 10km of road cuts which are between 10 and 35m high, making traditional mapping methods tedious. High resolution images taken by UAV were used to construct 3D geological models of the rock masses using the Agisoft Metashape software from which structural data such as dip, dip direction, joint roughness, joint spacing, etc. were extracted by use of the PointStudio software by Maptek. The extracted parameters were found to be consistent with data collected by traditional mapping methods. The digital data was supplemented with field data on groundwater conditions, weathering and rock strength and served as the basis for detailed stability analysis of rock slopes along the road using the Rocscience software suite. This workflow is found to be efficient, reliable, and allowed for the collection of data over large areas in a rapid manner. This methodology as an excellent supplement to traditional field mapping methods in areas of steep and high slopes with low access.
The stability analysis of rock slopes relies on the accurate collection of structural geological and geomechanical data as rock slope stability is often structurally controlled. This is usually done by traditional mapping methods on outcrops and slopes. In large projects and in areas of rugged and high topography with limited access, this task is often time-consuming and sometimes completely impractical. In recent years, several attempts and advances have been made in the use of photogrammetry as a tool in the collection of such data at various scales. In this study, we present the systematic collection of structural data from 3D models derived from high resolution drone imagery compared with data from traditional methods to test the viability of this method on an active construction project and to form the basis of further stability assessments.
